Engineering Poly(lactide)–Lignin Nanofibers with Antioxidant Activity for Biomedical Application

Abstract

Biodegradable poly(lactic acid) (PLA)−lignin composites are considered to be promising renewable plastic materials toward a sustainable world. The addition of lignin to PLA may assist to combat the oxidative stress induced by PLA as biomaterials. In this study, PLA−lignin copolymers with various contents of alkylated lignin (10−50%) were synthesized by ring-opening polymerization. The molecular weight of such copolymers ranged from 28 to 75 kDa, while the PLA chain length varied from 5 to 38. These PLA−lignin copolymers were further blended with poly(Llactide) (PLLA) and fabricated into nanofibrous composites by electrospinning. The PLLA/PLA−lignin nanofibers displayed uniform and bead-free nanostructures with fiber diameter of 350−500 nm, indicating the miscibility of PLLA and lignin copolymers in nanoscale. Unlike bulk materials, incorporation of PLA−lignin copolymers did not enhance the mechanical properties of the nanofibrous composites. Antioxidant assay showed that the lignin copolymers and PLLA/PLA−lignin nanofibers rendered excellent radical scavenging capacity for over 72 h. Moreover, three different types of cells (PC12, human dermal fibroblasts, and human mesenchymal stem cells) were cultured on the electrospun nanofibers to evaluate their biocompatibility. Lignin-containing nanofibers exhibited higher cell proliferation compared to neat PLLA nanofibers. PLLA/ PLA-Lig20 nanofibers displayed the best biocompatibility as it achieved a balance between the antioxidant activities and the cytotoxicity. With excellent antioxidant activities and good biocompatibility, the PLLA/PLA−lignin electrospun nanofibers hold great potential to be used as biomedical materials for protecting cells from oxidative stress conditions.

Multifunctional pH‐Responsive Sprayable Hydrogel Based on Chitosan and Lignin‐Based Nanoparticles

“…These results proposed that lignin molecular aggregation does not lose the inherent antioxidant activities of lignin. A plenty of hydroxyl and methoxy groups of lignin would assist to donate hydrogen to terminate oxidation propagation reaction . In addition, we noted that LNPs and LRNPs do not showed the outstanding antioxidant activities.…”

“…A plenty of hydroxyl and methoxy groups of lignin would assist to donate hydrogen to terminate oxidation propagation reaction. [17,18] In addition, we noted that LNPs and LRNPs do not showed the outstanding antioxidant activities. However, after complexing with CS, the antioxidant activities of the hydrogels were improved significantly.…”

“…Rheological Studies: DPPH assay is the general method to evaluated antioxidant activities. [18,24] Each sample (0.5 mL) was configured into different concentration gradients, and then mixed with 3.5 mL of DPPH radical solution. Absorbance at 517 nm was measured after 60 min in an incubator at 37 °C for three times.…”

Systematic in vitro biocompatibility studies of multimodal cellulose nanocrystal and lignin nanoparticles

“…Due to the highly negative surface charge of both materials, they form a welldispersed colloidal suspension in aqueous media, which can prolong the circulation of CNC and lignin NPs in bloodstream as well as reduce the nonspecific interaction with plasma proteins in vivo (Monopoli et al, 2011;Pino et al, 2014;Tenzer et al, 2013). In a few preceding reports, nanoscale cellulose and lignin have been shown to be relatively nontoxic and well tolerated in cell models (Clift et al, 2011;Jorfi & Foster, 2015;Kai et al, 2016). In a few preceding reports, nanoscale cellulose and lignin have been shown to be relatively nontoxic and well tolerated in cell models (Clift et al, 2011;Jorfi & Foster, 2015;Kai et al, 2016).…”

“…The cytotoxicity, biocompatibility, and fate in vivo are major concerns in the development of nanomaterials for biomedical applications (Seabra, Bernardes, Favaro, Paula, & Duran, 2018). In a few preceding reports, nanoscale cellulose and lignin have been shown to be relatively nontoxic and well tolerated in cell models (Clift et al, 2011;Jorfi & Foster, 2015;Kai et al, 2016). However, as any chemical modification is likely to affect the physicochemical properties of the material important for the biocompatibility and cellular interactions, such as surface chemistry, morphology, degree of crystallinity, and dispersion stability, the biocompatibility of any new nanomaterial construct should be rigorously evaluated before in vivo use (Frohlich, 2012;Verma & Stellacci, 2010).…”